Airfoil slot



g 4 v E. F. ZAP

, AIRFOIL' SLOT Original Filed March 11, 1938 1 INVENTOR, Edward 22' BYATTORNEY Patented Aug. 12, 1941 UNITED STATES PATENT OFFICE AIRFOIL SLOTEdward F. Zap, Westwood Village, Calif. Original application March 11,1938, Serial No.

Divided and this application August 30, 1939, Serial No. 292,726

1 Claim.

This application is a division carved out of application Ser. No.195,381, filed March 11, 1938.

This invention relates to wings of airplanes with variable aerodynamiccharacteristics, so that they can be modified by the pilot during flightfor giving best service during the various maneuvers. The inventionincludes the use of my novel modification by way of quasi ailerons forobtaining lateral control,

My novel airfoil modification device has a great many advantages, all ofwhich cooperate with each other so as to make each single advantage ofpeculiar value. It requires control displacement motions and controlforces of moderate magnitude. It acts quickly and without undue delay.It includes in its effects a-very quick and thorough lift elimination orlift spoiling, so conveniently obtained that it is feasible andcontemplated to connect the control for lift spoiling with the controlfor the wheel brakes, so that the lift is automatically spoiled wheneverthe wheel brakes are actuated, and the wheel brake action therebymultiplied in effectiveness. My wing control is free from icingtroubles, because in neutral position no narrow passages remain open andgive opportunity to ice to deposit.

My wing modifying device can be used for replacing the conventionalailerons. It offers then the considerable advantage of partly or evenwholly eliminating the unfavorable yawing moment associated with thecreation ofa lateral moment by conventional ailerons, That is to say, mynovel lateral control does not tend to turn the airplane about avertical axis so that the wing lifted up is retarded.

My novel lateral control offers distinct advantages in cooperation withflap means serving as high lift devices. It permits extending such flapsall the way from one tip to the other, leaving them fully operativethrough the entire span. It does not restrict the flaps or the region oftheir full operativeness toextend from the inner end of one aileron orquasi aileron to the inner end of the other aileron or quasi ailerononly.

Another advantage of my control used in such cooperation resides in achangeableness of the control capacity for equal displacement of thecontrol. The control capacity is different according to Whether theairfoil is in its high lift or in its low drag condition in such mannerthat the control capacity is larger with high lift, that is at lowspeed, than with low drag, that is at high speed. That is a considerableadvantage.

For with conventional airplanes, there is an excess of lateral controlat high speed, inviting danger of.overcontrol, and there is a scarcityof lateral control at low speed, interfering with good maneuverability,just when that is most desired. My control ameliorates both defects.

' It is the object of my invention to provide for airfoil lift variationmeans having all these advantages, or any of them by itself or incombination.

That is accomplished by providing the wing with slot means adapted toemit at the top side of the airfoil an air jet in forward direction,that is opposite to the direction of air flow. That jet may be turned onor off by the pilot. As an alternative and further improvement,forwardly directed jets and rearwardly directed jets are provided, andare put under the control of the pilot. The slot means extendsubstantially in spanwise direction. A single passage may often besufficient, but the invention can also be used with multiple or branchedpassagesserving as slots. The slot is preferably positioned behind themajor portion of the airfoil section. For lateral control, at least twosuch jet emitting slots are contemplated, one at each wing, preferablyextending into the tip regions. It is preferred to employ forwardly andrearwardly discharging exits at each side, and to create a lateralcontrol moment by simultaneously discharging a forwardly directed jet onone side and arearwardly directed jet on the other. During the laterphases of landing, the lift of both wings is spoiled by discharging aforwardly directed jet on both sides. The contact between the ground andthe moving or motionless airplane is thereby greatly improved.

These and other desirable objects and advantages of the presentinvention will be illustrated in the accompanying drawing and describedin the specification, certain preferred embodiments being disclosed byway of illustration only; for, since the underlying principles may beincorporated in other specific devices, it is not intended to be limitedto the ones here shown, except such limitations are clearly imposed bythe appended claim. r

'In the drawing, like numerals refer to similar parts throughout theseveral views, in which:

Fig. 1 is a partial cross section through the trailing edge portion ofan airfoil, incorporating the invention,

Figs. 2 and 3 show the upper portion of Fig. 1 with the slot closingdevice in different characteristic positions, and

Fig. 4 represents a plan view of the mechanism of Fig. 1, seen from theinside of the wing, looking upwardly.

In Fig. 1 there is shown the rear portion of an airfoil designatedbroadly by 20, and having a trailing edge 31. The inside of the airfoilcommunicates with the outer air space through an upper spanwiseextending exit slot 25 and through a corresponding lower slot entrance21. This entrance, this exit, and the inside of the wing communicatingtherewith, in unison, constitute slot means 35 broadly. The same arepositioned behind the station of maximum thickness of the airfoil.Entrance 21 is adjacent the trailing edge 3'! and in rear of exit 25.The airfoil 20 is provided with a flap 23.

During steady straight flight, the upper slot exit 25 is tightly closedby a cover member 50. This is shown in Fig. 1, cover 59 being then flushwith wing wall 3!. A plurality of pairs of arched rods v| and 52 extendthrough the wing wall 3|, through apertures 53, the forward end of, 52being hinged to wing wall 3| and. its rear- ,ward end being hinged tocover 56, and, conversely, the rearward end of 5| being hinged to thewing wall, and its forward end to the cover. Fastened to the cover is alever 40 hinged at ll to the pushrod 42, and a tension spring 54 isprovided to positively draw the cover downwardly, the spring connectingthe fixed wing structure with the end of lever 40. If pushrod 42 isshifted rearwardly, cover 50 is turned about its forward edge, and itstrailing edge is lifted up, into position shown in Fig. 2, forming thena rearwardly open slot exit. If pushrod 42 is shifted forwardly, cover50 is turned or rotated about its rearward edge, and its leading edge islifted up, into position as shown in Fig. 3, forming then a forwardlyopen slot exit, 25.

Fig. 2 represents the cover in the high lift position, Fig. 3 in the lowlift or spoiled lift position.

I claim:

In an airplane, an airfoil having means including a substantiallyspanwise extending slot in the upper surface of the airfoil connectingthe space over the airfoil with the space below it, a cover over theslot mounted rotatable about its forward edge androtatable about itsrear edge, and control means operable by the pilot during flight forturning the cover selectively about either of said edges from itsneutral position flush with the airfoil top.

EDWARD F. ZAP.

